fintstone asked me to start a thread with instructions on how to recharge a deeply-discharged (below 10.5 volts) Optima battery.

Virtually any standard automotive battery charger on the market will charge an Optima battery just fine. However, most automotive battery chargers will not charge any battery that has been discharged below 10.5 volts. If a standard flooded battery is discharged below 10.5 volts, there’s not much of a chance that it will be serviceable again. However, AGM-style batteries, like Optimas, can be recovered from a deeply-discharged state, by using an AGM-specific charger or by parallel charging.

To charge a deeply-discharged Optima with a regular charger, you can wire a second fully-charged automotive battery (12V+) to the discharged Optima in parallel (+ to + and – to –). Then hook up the charger to either battery, setting the charger at 10 amps for 2 hours and monitoring it frequently.

When the discharged Optima reaches 10.5 volts or more, remove the second battery and continue charging the Optima until fully charged.

Typically we recommend charging at a relatively low current, such as 2 amps, but when a battery has been deeply discharged, some sulfation of the battery plates may have occurred. However, if you charge at 10 amps, the higher current will help to break up sulfation that may have occurred. If you have an automatic charger, let it run until the charger indicates charging is complete. If you have a manual charger, estimate charging time by multiplying the capacity (amp hours or Ah) of the battery by 1.2 for a rough estimate of charging time in hours.

In most cases, these steps will recover an Optima battery. It’s ok for the Optima battery to get slightly warm during the charging process, but hot to the touch or hissing from the battery indicates a short and the process should be discontinued. If you are able to fully charge the battery, but it gradually loses it's charge (without any loads on it) over 12-24 hours, the battery is probably not recoverable.

If you’d rather not deal with this process, you can always take your battery to a professional battery specialist, like Interstate, who knows AGM technology. Most of them are willing to provide “charge and check” procedures for a small fee and many will provide the service for free.

If you have any other questions, I’ll do my best to answer them. I appreciate your interest in Optima batteries!

Jim McIlvaine
eCare Manager, OPTIMA Batteries, Inc.

Last edited by OptimaJim; 12-28-2009 at 10:28 AM..
Reason: clarification on charging instructions

what about the regular (not in this group) guy with only one car? i have read threads about hitting the dead battery with the "start" mode of the battery charger for a few minutes (hours?) to wake it up...no bueno?

I always JOLT my Optima from another car or the start mode and then put it on trickle charge 2amps until fully charged. It seems to work, is this ok? Although the best is to leave an automatic trickle charger on it when out of use for more than a week.

Thanks Jim! So basically one needs to connect the optima to a standard battery with jumper cables and then connect the charger to the standard battery.

__________________
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tcar, thanks for pointing that out. I did edit my original post to clarify the instructions. You can hook the charger up to either battery, as long as they are both connected in parallel.

dad911, I'm not sure what you consider "a large surge of current," but we recommend no more than 10 amps for Optima batteries. Some battery chargers cannot detect batteries that aren't at 10.5 volts or more. Parallel charging allows that to happen. I'm not allowed to discuss specific improvements we make to either our batteries or our production process, but when we do make changes to either, we do so to improve the end product for our consumers. One thing that has changed over the last six to seven years is an explosion in the use of aftermarket electronics, like mp3 players and GPS systems, which will put an additional draw on any battery, if they are left plugged in when the vehicle is parked. No battery manufacturer has figured out how to achieve a 100% success rate in their production process. However, if your vehicle has had more than one battery fail in less than a year, there may be some other issues contributing to those failures.

vash & RSTarga, there are a wide variety of chargers on the market with a variety of settings. Charger A's "start mode" might have totally different settings than Chargers B, C and D. Some chargers have "gel" or "gel/AGM" settings, which should not be used on Optima batteries and will damage them over time.

As I mentioned before, virtually any standard automotive battery charger will charge an Optima that reads at least 10.5 volts. If you are looking for a battery charger or a battery tender/maintainer it is very beneficial to get one that is microprocessor-controlled and has "AGM" compatibility. If it has a separate setting for AGM batteries it will enhance the battery’s performance and potentially extend the life. In addition, make sure that the device has protection to prevent overcharging.

....
dad911, I'm not sure what you consider "a large surge of current," but we recommend no more than 10 amps for Optima batteries. ......

One thing that has changed over the last six to seven years is an explosion in the use of aftermarket electronics, like mp3 players and GPS systems, which will put an additional draw on any battery, if they are left plugged in when the vehicle is parked.

......

Jim McIlvaine
eCare Manager, OPTIMA Batteries, Inc.

Jim,
When you parallel a fully charged battery to the discharged Optima, there will be a large surge of current, certainly in excess of 10 Amps. In fact, standard practice dictates dissimilar batteries should not be paralleled, only like batteries with similar charge.

I am not talking about a car equipped with 'new' devices. I have track cars, battery is disconnected through a cut-off switch between uses. In 2 recent occasions, Optimas have lasted less than a year, when in the late 1990's I got over5 years from one.

Jim,
When you parallel a fully charged battery to the discharged Optima, there will be a large surge of current, certainly in excess of 10 Amps. In fact, standard practice dictates dissimilar batteries should not be paralleled, only like batteries with similar charge.

I am not talking about a car equipped with 'new' devices. I have track cars, battery is disconnected through a cut-off switch between uses. In 2 recent occasions, Optimas have lasted less than a year, when in the late 1990's I got over5 years from one.

dad911, dissimilar batteries should not be installed in a vehicle in a parallel configuration. However, the parallel configuration detailed here is for the purpose of recharging a deeply-discharged battery with a standard battery charger. In this charging scenario, there will not be a large surge of current, provided the charger does not exceed 10 Amps.

Battery maintainers/tenders are an excellent investment for vehicles that are stored for any period of time. Even if these are not used, it's a good idea to check the voltage when vehicles are put into storage, to ensure that batteries are fully-charged and then periodically check the voltage during storage, to make sure they maintain at least 12.4 volts.

..... In this charging scenario, there will not be a large surge of current, provided the charger does not exceed 10 Amps.......

Jim McIlvaine
eCare Manager, OPTIMA Batteries, Inc.

Jim, If I can demonstrate that when you put a charged wet battery in parallel with the discharged Optima, the charging current(surge) from the wet cell to the Optima will exceed 10 Amps, will you send me (2) Optima batteries to replace the 2 I have that didn't last?

Jim, If I can demonstrate that when you put a charged wet battery in parallel with the discharged Optima, the charging current(surge) from the wet cell to the Optima will exceed 10 Amps, will you send me (2) Optima batteries to replace the 2 I have that didn't last?

Even if that happened (counter-emf won't allow that on a discharged battery), it's the same effect as connecting a large current battery charger on a dead battery, Optima or not. Sustained high amperage charge will create heat which isn't desirable, but the connected and charged battery won't be able to sustain the same charging rate as a battery charger will. It will merely.... discharge.

However, if the discharged battery was also defective, i.e. shorted cell, then the internal resistance will be abnormally lower and allow more current to flow through it and perhaps cause further damage and heat.

fintstone asked me to start a thread with instructions on how to recharge a deeply-discharged (below 10.5 volts) Optima battery.

Virtually any standard automotive battery charger on the market will charge an Optima battery just fine. However, most automotive battery chargers will not charge any battery that has been discharged below 10.5 volts. If a standard flooded battery is discharged below 10.5 volts, there’s not much of a chance that it will be serviceable again. However, AGM-style batteries, like Optimas, can be recovered from a deeply-discharged state, by using an AGM-specific charger or by parallel charging.

To charge a deeply-discharged Optima with a regular charger, you can wire a second fully-charged automotive battery (12V+) to the discharged Optima in parallel (+ to + and – to –). Then hook up the charger to either battery, setting the charger at 10 amps for 2 hours and monitoring it frequently.

When the discharged Optima reaches 10.5 volts or more, remove the second battery and continue charging the Optima until fully charged.

Typically we recommend charging at a relatively low current, such as 2 amps, but when a battery has been deeply discharged, some sulfation of the battery plates may have occurred. However, if you charge at 10 amps, the higher current will help to break up sulfation that may have occurred. If you have an automatic charger, let it run until the charger indicates charging is complete. If you have a manual charger, estimate charging time by multiplying the capacity (amp hours or Ah) of the battery by 1.2 for a rough estimate of charging time in hours.

In most cases, these steps will recover an Optima battery. It’s ok for the Optima battery to get slightly warm during the charging process, but hot to the touch or hissing from the battery indicates a short and the process should be discontinued. If you are able to fully charge the battery, but it gradually loses it's charge (without any loads on it) over 12-24 hours, the battery is probably not recoverable.

If you’d rather not deal with this process, you can always take your battery to a professional battery specialist, like Interstate, who knows AGM technology. Most of them are willing to provide “charge and check” procedures for a small fee and many will provide the service for free.

If you have any other questions, I’ll do my best to answer them. I appreciate your interest in Optima batteries!

Jim McIlvaine
eCare Manager, OPTIMA Batteries, Inc.

You'll making several assumptions,....DANGEROUS ASSUMPTIONS!

You're assuming that the "fully" discharged battery will not quickly accept a high current charge rate, your "hot to the touch or hissing" statement indicates that you are well aware of the potential.....

DANGER!

Set the scene: Gas water heater and/or gas furnace in an attached garage. Hook up the batteries as you state, listen/feel, no heat or hissing, walk away.